staging: comedi: adv_pci1710: separate out PCI-1720 support as a new driver

staging: comedi: adv_pci1710: separate out PCI-1720 support as a new driver

The PCI-1710 series boards are multifunction data acquisition boards with
analog inputs and outputs, digital inputs and outputs, and counter/timer
functions.

The PCI-1720 is a simple 4 channel analog output board. It also uses a
unique register map.

Separate out the PCI-1720 support as a new driver, adv_pci1720, to ease
maintainability.

Fix some issues with the PCI-1720 support in the new driver:
  1) the registers are all 8-bit
  2) remove the analog output "reset" when the driver attaches/detaches
  3) disable "synchronized output" to simplify the analog outputs
  4) remove the need for the private data
  5) add support for the BoardID register to allow multiple cards

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>